The St. Louis Breast Cancer Tissue Registry is one of four institutions that have collaborated for the past 9 years to form the Cooperative Breast Cancer Tissue Resource of the National Cancer Institute. The mission of this group has been the organization, evaluation, maintenance, and distribution of archival breast cancer specimens coupled with detailed data on clinical treatment, outcome, and tumor pathology to facilitate research investigations of new diagnostic and prognostic tumor markers. The significance of tumor marker expression data is greatly enhanced by the extensive case data compiled from cancer registry records, clinical charts, pathology reports, and >5 years patient follow-up for recurrence and vital status. With more than 9000 specimens from 4, geographically and ethnically, diverse regions of the US, the CBCTR provides a unique collection, representative of community medical center patient populations, for evaluation of breast cancer markers that is not readily available to investigators at single medical institutions or biotechnology companies. The combined expertise of the Pl's at the CBCTR institutions include clinical oncology, breast tissue pathology, clinical laboratory operations, clinical trials, and shared resource & cancer research laboratories. Continuing audits of clinical data and tumor classification, development of new tissue screening technologies (tissue microarrays), significant scientific and statistical review of applications for use of the Resource specimens, and moderate service fees further add to the exceptional value of this Resource in the support of many research studies. Over the next 3 year period we will continue to fulfill the responsibilities of a cooperative agreement including 1) work with all members of the CBCTR in a coordinated structure to provide existing tissue and data to researchers, 2) work with all CBCTR members to provide specimens for design and construction of Tissue Microarrays as recommended by the NCI and Research Evaluation Panel (REP), 3) continue to monitor, update, and communicate, with the IMS Central Database, the collection of data linked to our cases, 4) cooperate with all sites, NCI, IMS, and REP members to achieve NCI goals and to publicize this Resource to the cancer research community, and 5) to plan the acquisition and data collection for additional breast cancer tissues, either archival or fresh/frozen, to replenish our finite collection.